1. Field of the Invention
The invention relates to an antenna adjustment method, system and network element of a communication system.
2. Description of the Related Art
In Code Division Multiple Access (CDMA) networks where all the cells share the same frequency, the planning of cell service areas is critical. If the overlap of two CDMA cells is increased, the quality degradation due to interference also increases, as the processing gain does not totally eliminate the influence of the interference. The size of a radio cell can only be affected without hardware changes by changing the transmitted power or antenna configuration (e.g. antenna tilting or antenna bearing). Changing the power potentially requires a base station reset which means clearing the cell of traffic. A base station is also called a node B in UMTS (Universal Mobile Telecommunications System). Additionally, reducing cell power will decrease the received power throughout the cell area, not only on cell edges. Antenna bearing is usually costly to change.
The prior art method for finding out a suitable antenna tilting is based on planning tool predictions on cell service areas. Drive test measurements have been used to complete planning tool results, but this is expensive and time consuming. Each sector has several possible tilt angles for an antenna: the total number of different tilt configurations is AB (A to power B), where A is the number of different tilt settings per cell and B is the number of cells in the network. For a large city, this number of different tilt configurations might be in the order of 101000. As can be seen, the problem is that, in practice, it is impossible to try all antenna tilting combinations or even a significant portion of them to determine the best configuration.